The extreme heat makes everyone move slower, and the trains carrying them home from work today will be moving slower too.

For the second day in a row, Metro North Railroad has announced a slow-down of its electric-powered trains to protect the overhead lines and equipment from damage.

The measure will add about 15 minutes to most trips between Grand Central Terminal and New Haven. Metro-North says portions of the overhead catenary system on the main New Haven line date to 1914. The system is prone to failure in extreme heat, which can causes wires to sag, a spokesman said.

Sagging wires can become entangled in the "pantographs" -- the mechanical arms on the top of the cars that collect the power and provide it to the train -- both disabling the train and potentially tearing down wires that would require sections of track to be taken out of service, railroad officials said.

To limit the likelihood of damage to remaining older sections of the New Haven Line's catenary system, the railroad has established restrictions when temperatures reach higher than 80 degrees.

The heat is only one of three different factors disrupting service Friday. Power was restored on Metro-North's New Haven Line between New Haven and Stratford by 6 a.m. Friday, hours after an electrical transformer fire shut down power to about 11 miles of track .

Metro-North was forced to use diesel locomotives on that stretch.

Electricity was restored shortly before 6 a.m., and the 5:48 from New Haven came through Milford about 10 minutes behind schedule. The 6:05 a.m. was five minutes late and had only four cars.

The diesel-powered trains had been used at the start of the morning rush to shuttle Manhattan-bound passengers to Bridgeport, where they switched to the usual electricity-powered trains to Grand Central Terminal.

The 4:21 didn't stop in Milford at all, said Jack Finn, who manages the station coffee shop. The 4:48 was a diesel train on the other side of the tracks and the 5:21 came through Milford without stopping, he said.

The next trains, running on the overhead catenary system, were a bit late but gradually service caught up to the timetable. Italo Centore, who commutes weekdays from Milford to his job in Greenwich, said he'd heard about the transformer fire before he left his house. "I figured it'd be all right," he said. "I haven't had any problems yet."

"It's always something," Doyle said as he waited for the 6:35. "If it's not the heat it is too wet or too cold. The new train cars are nice, when you can get them."

A few minutes later, while the electronic signboard still promised "good" service an announcement was made that the 6:53 express was cancelled, and that the 7 a.m. local would leave on the other side of the tracks.

It was a rough morning for the country's second-largest commuter railroad. Service on its Hudson line was suspended Friday until further notice due to a freight train derailment. "Customers are strongly recommended to make alternate service plans,'' said an advisory on the Website.

Amtrak also slowed trains along the Northeast corridor because of the heat on the tracks. The high temperatures would also slow Metro North trains for the trip home Friday afternoon.

For veteran rider Jack Fowler Friday's situation seemed familiar. "Metro North is so incredibly blanked up this morning,'' he posted to Facebook. "First train canceled, next train delayed, other track, then held in Bridgeport, Keystone Kop rescheduling, Get off the train ... Wait! Get back on. Wonder what they have in store for us on the commute tonight.''